1. Field of the Invention
The present invention relates to a method of removing an exogenous endocrine-disrupting chemical (hereinafter referred to as an “environmental hormonal substance”) in water, and more particularly, to improvement in the performance of removing the environmental hormonal substance by using a microorganism-immobilized carrier.
2. Description of the Related Art
Chemical substances having in-vivo endocrine-system disrupting activities are present in wastewater such as sewage water and seepage water from landfills. They act as environmental hormonal substances, causing problems. The endocrine systems of living organisms are disrupted by the presence of these environmental hormonal substances, with the result that abnormal reproductions and gender changes from male to female occur, having significant effects upon the ecosystem. The endocrine system of living organisms reacts with extremely sensitivity to such chemicals at certain period of their growth. In humans, the sensitivity is high particularly in fetuses and infants. The effects of the environmental hormonal substances upon them have been a cause of concern. Most environmental hormonal substances are detected at concentrations in the order of several tens μg/L to several ng/L. Although most of environmental hormonal substances are detected in extremely low amounts, they must be disposed of as much as possible in consideration of their effects on the ecosystem as mentioned above.
In the meantime, the environmental hormonal substances present in water can be decomposed to some extent by a biological treatment such as a conventional activated-sludge process. However, the biological treatment has a drawback in that since the environmental hormonal substances are present in extremely low concentrations, they cannot be completely decomposed by microorganisms. To improve the efficiency of the biological treatment, there is a method of maintaining a large amount of microorganism in a reaction vessel by depositing them onto a carrier or immobilized within a carrier. This method is effective in reducing nitrogen or BOD in wastewater, but ineffective in removing the environmental hormonal substances.